As resins for forming resin surface layers of electric appliances, decorative products and interior parts of automobiles, resins of high surface glossiness such as polystyrene, an acrylonitrile/butadiene/styrene copolymer (ABS resin), polycarbonate, polyalkylene terephthalate and polyvinyl chloride are widely employed.
Some of the resin surface layers are provided on an expanded resin material which is excellent in heat insulation and impact resistance. In the case of providing the resin layer of high surface glossiness on the expanded resin material, the resin surface layer of high surface glossiness is generally laminated on an expanded resin material obtained by expanding a resin using an expanding component such as a fluorine-containing solvent. However, resins used for forming the surface layer of high surface glossiness are not sufficient in resistance to the expanding component. Therefore, when a product having a surface layer made of such resins is used for a long period of time, various characteristics of the resin surface layer, particularly surface hardness, rigidity and surface glossiness, are apt to deteriorate For example, when the surface layer is kept under severe conditions such as a low temperature for a long period of time as in the case of linings of electrical appliances wherein heat insulation of high level is demanded, the characteristics of the surface layer deteriorate, resulting in not only the reduction of surface glossiness but also in the occurrence of cracks.
For solving such problems on the resin surface layer, an attempt to modify the resin used for forming the surface layer has been made, but the effect of this attempt is not necessarily satisfactory